Geoege habtje akd fbedebick haetje



UNITED STATES PATENT OFFICE.

GEORGE HARTJ E AND FREDERICK HARTJE, OF NEW YORK, N. Y.

MANUFACTURE OF GOLD FOR JEWELRY.

SPECIFICATION forming part of Letters Patent No. 281,059, dated July 10, 1883.

Application filed February 9, 1883. (Specimens) T 0 all whom it may concern:

Be it known thatwe, GEORGE HARTJE and FREDERICK HART-JE, of the city, county, and

State of New York, have invented a new and useful. Improvement in the Manufacture of Gold to be used in Jewelry, whichis fully set forth in the following specification.

The following is a description of our invention: The gold, mingled with its alloy in the usual manner, is melted and rolled out in strips or pieces of the proper shape, and then gas or other flame is applied to the gold by means of a blow-pipe. In order to produce the best result the extreme point of the flame should alone come in contact with the gold After applying the flame for a certain length of time, which varies with the degree of heat, and somewhat with the thickness of the metal strip, the gold will begin to blister. Ahigher degree of heat concentrated on a more confined surface is needed to produce blistered gold than to produce what is known as sweated gold, and care must be taken not to apply the heat for such a length of time or to such a degree that the gold will be melted. The result of the blistering is that little inequalities, which are mostly porous internally, are formed upon the surface of the gold, probably I by reason of the great Variance between the temperature of the gold at the point where the flame strikes it and the remainder of the gold.

This porosity often extends inward to a considerable distance. The flame should successively be applied to all portions of the gold which it is desired to blister. The result is that the gold acquires avery beautiful appearance, which, especially in combination with precious stones, is very pleasing to the eye. The appearance somewhat resembles that of gold filings soldered onto a piece of metal. The blistcred gold, however, is much more beautiful. Experience shows the greatest variety in the shape and form of the irregularities produced by the blistering, and it is almost impossible to make two pieces exactly alike. Moreover, the blistered gold is smooth, whereas the soldered gold filings are rough, which, in articles of jewelry like sleeve-buttons, for instance, is very objectionable. The blistered gold is also much more durable. Soldered filings cannot be shaped after they are'soldered, whereas the blistered gold can be shaped after it has been blistered. Filing the gold will produce almost the same result; but the roughness thereby obtained is objectionable, and it is more expensive to produce, and there is less variety in its ap 'aearance. The effect produced is much better and more pleasing in gold with a copper alloy than in gold with silver alloy. A good effect is produced in each kind of alloy where the gold is from fourteen to sixteen carats of fineness.

When forming an article with a hollow curved part, it is necessary to support the under side'of the blistered gold with ocher or plaster-of-paris mixed with water, which is removed after it cools. The office of the ocher 0r plaster-of-paris is to support the gold while heated and prevent its losing its shape.

What we claim, and desire to secure by Letters Patent, is"

1'. As a new article ofmanufacture, blistered gold made substantially as herein described.

2. The method of blistering gold, substantially as herein described.

In testimony whereof we have signed this specification in the presence of two subscrib- ,ing witnesses.

GEO. HARTJE. FREDERICK HARTJ E.

Witnesses:

J OHN MOGLURE, R. A. PIPER. 

